The present invention relates generally to cellular antennas and more particularly to a cellular antenna for receiving global positioning satellite signals in addition to transmitting and receiving cellular signals.
The increased utilization of the Global Positioning Satellite (GPS) system for non-military applications has created a significant market targeted at the average consumer. The GPS system can relay position, speed and height with high precision and accuracy to a user. One such application is the ability to relay both to a mobile user and to a base station the user's position during a call from a personal cellular telephone.
The frequency allocation for GPS is approximately 1540 MHZ. The frequency allocation for the Advanced Mobile Phone System (AMPS) is approximately 824-890 MHZ, and approximately 900-950 MHZ for the Global System for Mobile Communications (GSM). The differences in the frequencies of almost an octave and the fact that the cellular system communicates terrestrially, while the GPS system communicates via satellite, mandates that the antenna designs be completely different. The use of the two individual antennas is cosmetically un-attractive and requires almost double the installation effort in respect to mounting and cable routing.
A second problem exists with conventional cellular 1/4 wave whip type antennas. Conventional cellular antennas aim their signal from zero to thirty degrees above the horizon. Communications is often lost in mountainous areas, where reception is required at elevation angles above thirty degrees.
The present invention is therefore directed to the problem of developing a combined cellular and GPS antenna while enabling reception at higher elevation angles than conventional cellular antennas.